Influenza hemagglutinin: Difference between revisions
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====HA2==== | ====HA2==== | ||
The HA2 chain is primarily resposible for facilitating membrane fusion. The C-terminal end of the protien is embedded in the viral membrane. The N-terminal end, known as the "fusion peptide," consists of 10 hydrophobic amino acids. When the protein undergoes pH induced conformational changes, this fusion peptide becomes embedded in the host cell membrane. Additionally, the C- | The HA2 chain is primarily resposible for facilitating membrane fusion. The C-terminal end of the protien is embedded in the viral membrane. The N-terminal end, known as the "fusion peptide," consists of 10 hydrophobic amino acids. When the protein undergoes pH induced conformational changes, this fusion peptide becomes embedded in the host cell membrane. Additionally, the C-terminus embedded in the viral membrane rearranges, bringing the two membranes closer together and facilitation fusion. | ||
===pH Induced Conformational Changes=== | |||
After the virus has bound to the cell membrane, the cell engulfs the viral capsule through the process of endocytosis. Included on the lining of the endosome are ion pumps, were originally used to pump ions out of the cell and maintain a proper pH level. As a part of the endosomal lining, the pumps continue to pump ions, but now into the endsome. This causes the pH surrounding the viral capsule to become acidic. | |||
When the pH level reaches 5.5, the HA1 protien shifts its position, rearranging to allow the HA2 protein to access the endosomal membrane. The HA2 chain begins to rearrange, and the loop shown in blue refolds into a helix at pH5. | |||